If you’re here after completing the Secret Boss fight for Chapter 3, and need a helping hand to get to the Deltarune Chapter 4 secret boss fight, you’ve come to the right place. Luckily, there won’t be any S ranking involved or metaphors of abandonment and loneliness in the form of 8-bit video games. This one is relatively straightforward. It requires a bit of backtracking, so let’s get started.
How to unlock Chapter 4 Secret Boss - Deltarune Walkthrough
The chapter 4 secret boss fight is unblocked by finding three sets of sheet music that you need to play on the golden piano at the top of the old man’s study. In order to get the music sheets and complete the piano puzzle, you will need to have the climbing tools, which you get after fighting Jackenstein.
How to fight Jackenstein
You fight Jackenstein by progressing the game normally. Don’t worry, it’s not a difficult fight, and it won’t take too long to progress. After you’ve gotten the tools, we can now focus on getting the music sheets.
How to get Deltarune Music Sheet 1
This guide will show the location of all the music sheets and the musical notes you’ll need at the end. You can follow the guide to find the sheets yourself and see some fun story elements of Deltarune, or you can simply skip to the end and enter the notes for the piano puzzle.
- We will return to the old man’s study room and navigate backwards.
- On the previous screen, before the old man’s study, you will go down.
- Take a right until you find a room with a stool.
- After reaching this screen, you will take a left and keep going left until you find a climbable wall.
- Scale upwards and complete a climbing puzzle until you reach a barrel of water.
- Interacting with it won’t do anything; however, if you go backwards, you will initiate a mini-boss.
- The watercooler from Chapter 3 makes a grand return.
Most of the moveset is the same as Chapter 3, with one new move that surprised players. This is not a difficult fight—simply chat, flirt, and then use Ralsei to nuzzle with it until it can be pacified. After you defeat it, you will receive the first music sheet.
How to get Music Sheet 2 in Deltarune
Making your way back to the room with the stool, you will take a right this time. Moving past the first set of stained glass windows until you see the first climbable wall.
- After climbing to the top, you will find yourself in a dark maze.
- Navigating it is not difficult at all, as your footsteps will provide a visual cue of where everything is.
- On the right side of the room, you will find a yellow-tinted glow.
- After interacting with it, a northern passage will unlock with a yellow switch on the floor.
- Simply step on it, and you’ll receive the second set of notes.
How to get Music Sheet 3 in Chapter 4
We will no longer use the room with a stool for navigation purposes. Instead, we will be returning to the old man’s study for the third and last music sheet. You will go through the furthest left door at the top of the study and take another left past the screen with the save point.
- As is the trend with this route, you will take another left, in the room of moving books, until you see a waterfall.
- There is a hidden door behind the waterfall, which leads to another dark maze.
- Navigate through the maze in the same way as the previous one.
- Interact with every yellow switch and yellow visual queue until you find a blue switch on the floor.
- Step on it, and you will receive the last musical sheet, and with that, the third set of musical notes.
How to solve the Golden Piano Puzzle
The last part of the piano puzzle is The Golden Piano. Backtrack until you come back to the screen with the save point.
- Go to the furthest right wall, and start climbing.
- Keep climbing and you’ll reach the piano.
- Input the notes in order to unlock the Secret Boss room.
- As mentioned previously, you can simply skip everything and input the notes, since they are always the same.
Order of the notes in Golden Piano Puzzle:
Up, dot, up, left, down, dot, right, dot, right, down, left, dot
- After successfully playing the piano, head downwards to the main lobby of the study.
- You will see that a new room has opened where the story of the Magic Axe was told.
- Enter the room and fight the boss. You will gain the Magic Axe and another Shadow Crystal.
What Are Shadow Crystals in Deltarune? - All Known Theories
The Shadow Crystals are collectible items that you get after defeating secret bosses. Currently, they have no direct use, but they raise some interesting questions. If you use them in the Dark World, Kris will look through the shard and see the light world counterpart in its normal state. For example, if you use the shadow crystal in the Cyber World, you will see the normal computer lab.
We can theorize that these Shadow Crystals serve as a mirror into the “real world” outside of the escapism fantasy that Kris possibly built for themselves, allowing them to escape the harshness of reality.
What gives weight to this theory is the Glass item from the Light world. If Kris inspects it and looks through it, like they would the Shadow Crystal, they don’t see anything different. Since they are already in the “real world”, they don’t need to “snap back to reality” by looking through the shadow crystals. It is confirmed from Ralsei at the beginning of Chapter 3, that everything in the Dark World is simply an illusion of its real world counterpart.
Including Ralsei himself, more than likely being an illusion of Asriel who manifested from Kris’s mind after Asriel left for college, and left his younger brother alone in a broken family. It’s not too much of a stretch to speculate that Ralsei was born from Kris’s longing for love, since the only person who could provide said love has left.
All Deltarune Endings Explained
Confirmed by Toby “TOUHOU Project” Fox, Deltarune will have one ending, which has fans, myself included, scratching our heads. Even if we simply ignore the number of endings Undertale had, and solely focus on Deltarune, there are multiple instances of branching story elements, like the Snowgrave route.
In Chapter 2, you can initiate a darker route where Kris, or rather the player controlling Kris, manipulates members of the party, and as a consequence of their actions, sends Berdly to the hospital. In later chapters, if the player continues from their snowgrave save files, Berdly can still be found in a comatose state in the hospital bed.
Additionally, there is a hidden interaction between Kris and Noelle. In Chapter 4, before Noelle asked to privately talk to Kris, they hid their heart before leaving to talk with Noelle. The heart (the player) escapes and finds the two talking in a room. The player hijacks the conversation and Kris in order to continue the dark route. It is creepy and unsettling, and makes no sense as to how this would lead to the same ending as the regular route.
Some speculate that the snowgrave route is all in Kris’s head, but that seems a bit too far-fetched for now. We will simply wait for the other chapters and see for ourselves.
Will Deltarune Chapters 5-7 be free?
It has been confirmed that, after purchasing Deltarune, all future chapters will be free. Chapter 5 will more than likely be released in the first quarter of 2026, meaning we won’t have to wait years for the next story parts.
While you wait for the next chapter of Deltarune, you can also check out Bendy: Secrets of the Machine walkthrough here on Pro Game Guides.
